my thoughts on the size is if shes ready she will go, if not she will not. but with my animals i wait till i know her weight is up and if i feel she can handle it, im thinking weights of around 1300g and up. by that size they typically are big enough to breed but remember that a snake could be 1500 g but not have a good fat reserve and may not be a good idea to breed as she will have trouble with the fasting. if any of my snakes miss meals and or goes off feed and depends how long i take her out my breeding plans, unless she begines to eat again. so far so good i got some females from 1350g to 3500 g breeding this season but they are still pounding food back with no problems so im sure the smaller ones will put on weight in 2 or 3 months of feeding before they go off feed for the lay. but typiccaly after laying females become rat heads (crack heads) lol and start eating like theres no tomorrow.. well thats my thought on the topic feel free to comment..